Building ventilating system

ABSTRACT

In a kitchen, a ventilating hood is disposed over a cooking unit and has an exhaust duct and a return duct, both extending through the roof to the exterior. An exhaust blower is connected to the exhaust duct and an intake blower to the intake duct, outside the building. A by-pass duct extends from the exhaust blower outlet to the intake blower inlet and a damper in the duct is responsive to temperature sensed in the intake duct to by-pass a portion of the air handled by the exhaust blower into the intake blower for return through the hood to the area above the cooking unit. Filtering means are provided in the hood.

United States Patent [191 Brown [4 1 Apr. 2, 1974 211 Appl. No 274,324

[56] References Cited -UN1TF.D STATES PATENTS 3,513,766 5/1970 Ahlrich98/115 K 3,173,980 3/1965 Hysingcr 98/115 R Sweet et a1 i i 98/115 KSamuelson et a1. 98/115 LH Primary Examiner-Meyer Perlin AssistantExaminer-Ronald C. Capossela Attorney, Agent, or Firm-W00dard, Weikart,Emhardt & Naughton [57] ABSTRACT In a kitchen, a ventilating hood isdisposed over a cooking unit and has an exhaust duct and a return duct,both extending through the roof to the exterior. An exhaust blower isconnected to the exhaust duct and an intake blower to the intake duct,outside the building. A by-pass duct extends from the exhaust bloweroutlet to the intake blower inlet and a damper in the duct is responsiveto temperature sensed in the intake duct to by-pass a portion of the airhandled by the exhaust blower into the intake blower for return throughthe hood to the area above the cooking unit Filtering means are providedin the hood.

9 Claims, 1 Drawing Figure 1 BUILDING VENTILATING SYSTEM BACKGROUND OFTHE INVENTION 1. Field of the Invention This invention relates generallyto ventilating systems for buildings, and more particularly to means forremoving heat and fumes above a working surface wherein heat and fumesare generated, and returning a mixture of fresh air and a portion of theremoved air through the duct and back to the area over the workingsurface.

2. Description of the Prior Art Much has been done in ventilatingsystems. The problem with which my invention is particularly concernedis that of removing fumes and heat from a working surface in a building,and more particularly a cooking unit in a restaurant kitchen, forexample. Three United States patents of which I am aware and which dealwith this subject are as follows:

3,457,850 Sweet et al. July 29, 1969 3,496,704 Bandlow Feb. 24, 19703,530,784 Courchesne Sept. 29, I970 SUMMARY OF THE INVENTION Describedbriefly, in a typical embodiment of the present invention, a hood isemployed over a working surface where heat and fumes to be exhausted aregenerated. Exhaust means are connected to the hood for removing air fromunder the hood and exhausting it to the atmosphere outside. Intake meansare associated with the hood for drawing in fresh air from the outsideand introducing it adjacent a portion of the perimeter from theatmosphere and delivering it through the duct 19 to the chamber 31 overpartition 32 in the hood. From chamber 31 it passes through filter 33and is reintroduced through a slot 34 at the front of the hood. Thisslot can be extended around the sides of the hood, if desired, and incertain instances it may be found desirable to extend a slot completelyaround the entire of the hood. By-pass means are coupled between theexhaust and intake means to by-pass a portion of the air removed bytheexhausfrne'ansand return it to the intake means, avoiding the necessityof heating as much fresh air as is removed from the hood. Temperaturesensor means are provided in the intake means to control the damper inthe by-pass means and by-pass smaller amounts of air from the exhaustmeans to the intake means as the intake temperature rises.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE of drawing is asectional view through a kitchen in a buildingand illustrating a typicalembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT perimeter of the hood. In anyevent it is preferable to provide a slot at least along the frontportion of the perimeter of the hood as shown at 34 in the drawing.

According to the main feature of the present invention, a by-pass isprovided between the exhaust and intake. In the drawingit isaccomplished by the employment of a by-pass duct 36 between thedischarge end of the exhaust blower and the intake of the intake blower.-A pivotable damper 37 is provided at the entrance of the by-pass ductand is movable outwardly in the direction of arrow 39 to deflect aportion of the air being discharged from the exhaust blower. Thedeflected or diverted portion of the air passes through the by-pass ductin the direction of arrow 41 to the intake of the intake blower where itis mixed with fresh air also entering the intake at opening 24 andreintroduced through the duct l 9and the slot 34 to the area 43 over thecooking surface and under the hood.

Control of the damper 37 is effected by a link or other suitable means44 connected between a reversible damper control motor 46 and the damper37. The damper control motor is operated by a temperature sensor 47 inthe return duct 19. As the temperature of the air passing through thereturn duct 19 increases, the damper control motor is driven in onedirection to move the damper 37 in a closing direction opposite arrow39. Therefore, a larger percentage of fresh air is taken in. As the.temperature in the return duct 19 decreases, the damper control motor 46is driven in the opposite direction to move the damper in the directionof arrow 39 and increase the amount of air by-passed from the exhaustblower through duct 36 to the intake blower 23. This tends to raise thetemperature in the return duct 19. The arrow 48 in the line between thetemperature sensor 47 and the damper control motor 46 represents anadjustment useful to establish the desired temperature range in thereturn duct 19, for appropriate damper control motor response thereto.Sensors, and controllers useful for this purpose are well known andcommercially available.

From the foregoing description, it can be seen that by diverting part ofthe-heated air taken from the hood and reintroducing it, the need forfresh air through inlet 24 is reduced. Therefore the fuel requirement toheat such fresh air is reduced. This is particularly beneficial wherethe building employs a type of heat which is comparatively expensive. Ihave found that the bypassing of the air is not detrimental tocleanliness of operation and the only requirement is that the filter 27be kept reasonably clean. Accumulation of foreign matter on filter 33occursat a surprisingly slow rate. It

should be understood that a variety of types of filters can be employed,including the electrostatic type as well as others. Also the specificarrangement of ducting can be sufficient from that illustrated, theimportant aspect being the by-passing ofa portion of the exhaust airinto the intake system for introduction into the building.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

The invention claimed is:

1. In a ventilating system, the combination comprising:

a working surface;

a hood covering at least a portion of said working surface and having afront;

exhaust means having an outlet coupled to said hood and including anexhaust duct and intake blower means removing air from under said hood;

intake means including areturn duct and intake blower means introducingair at the front of said hood; and by-pass means coupled between saidexhaust means and said intake means to take a portion of the air fromsaid exhaust means, prior to discharge of that portion to atmosphere,and return it and reintroduce it at the front of said hood. 2. Thecombination of claim 1 and further comprising:

temperature sensor means in said return duct; a damper associated withsaid by-pass means; and damper operating means coupled to said sensormeans and to said damper and responsive to higher temperatures sensed insaid return duct to by-pass a smaller portion of air from said exhaustmeans.

3. The combination of claim 2 wherein:

said temperature sensor means is located to sense intake air temperaturein the intake means between the bypass means and a point where intakeair is introduced at the front of said hood.

4. The combination of claim 1 wherein said exhaust blower meansestablishes a flow of air in a path from said hood to said exhaustblower means, the combina- 4 tion further comprising:

first filter means positioned in the path of air from said hood to saidexhaust blower means.

5. The combination of claim 4 wherein said intake blower meansestablishes a flow of air in a path from said intake blower means to thefront of said hood, the combination comprising:

second filter means in the path of air from said intake blower meanspositioned to the front of said hood.

6. The combination of claim 1 wherein:

said hood and working surface are inside a building, and said worksurface is a heat generating cooking surface;

and said blower means are outside the building.

7. The combination of claim 6 wherein:

said blower means include an exhaust blower removing air from under saidhood, and intake blower drawing fresh air in from outside the building.

8. A ventilating system comprising:

a vent hood;

exhaust means having an inlet coupled to said hood and including anexhaust duct and exhaust blower means for removing air from under saidhood, and of sufficient length between said inlet and a point ofdischarge to-atmosphere to discharge removed air to the exterior of abuilding in which said hood may be disposed;

intake means including a return duct and intake blower means introducingair adjacent said hood, said return duct being of sufficient length toenable intake of fresh air from outside a building in which said hoodmay be disposed;

and by-pass means coupled between said exhaust means and said intakemeans to take a portion of air from said exhaust means upstream of saidpoint of discharge and return it and reintroduce it adjacent theperimeter of said hood.

9. The combination of claim 8 and further comprising:

temperature sensor means in said return duct;

a damper associated with said by-pass means;

and damper operating means coupled to said sensor means and to saiddamper and responsive to higher temperatures sensed in said return ductto by-pass a smaller portion of air from said exhaust means to saidintake means.

CUNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,800,689 Dated April 2, 1974 lnye t fl LESTER H. BROWN It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 3, line 4, "Sufficient" should read -different-- Column 3, line22, "outlet" should read --inlet-- Column 3, line 23 "intake" shouldread "exhaust-- Column 4, line 7, "combination comprising" should read"combination further comprising-- I Column 4, line 8, "filter means in"should read --filter means po'sitioned i Column 4, line 9, "meanspositioned to" should read --means Column 4, lines 37 and 38, "adjacentthe perimeter of said hood" should read ---adjacent said hood-- Signed,and sealed this 3rd day of September 1974.

(SEAL) Attestz v MCCOY M. GIBSON, JR, c. MARSHA-LL DANN AttestingOfficer Commissioner of Patents FORM PC4050 (IO-69) USCQMMQDC 5o37 .p 9v u.s. sovenuuzur PRINTING OFFICE I96, o-ass-su

1. In a ventilating system, the combination comprising: a workingsurface; a hood covering at least a portion of said working surface andhaving a front; exhaust means having an outlet coupled to said hood andincluding an exhaust duct and intake blower means removing air fromunder said hood; intake means including a return duct and intake blowermeans introducing air at the front of said hood; and by-pass meanscoupled between said exhaust means and said intake means to take aportion of the air from said exhaust means, prior to discharge of thatportion to atmosphere, and return it and reintroduce it at the front ofsaid hood.
 2. The combination of claim 1 and further comprising:temperature sensor means in said return duct; a damper associated withsaid by-pass means; and damper operating means coupled to said sensormeans and to said damper and responsive to higher temperatures sensed insaid return duct to by-pass a smaller portion of air from said exhaustmeans.
 3. The combination of claim 2 wherein: said temperature sensormeans is located to sense intake air temperature in the intake meansbetween the bypass means and a point where intake air is introduced atthe front of said hood.
 4. The combination of claim 1 wherein saidexhaust blower means establishes a flow of air in a path from said hoodto said exhaust blower means, the combination further comprising: firstfilter means positioned in the path of air from said hood to saidexhaust blower means.
 5. The combination of claim 4 wherein said intakeblower means establishes a flow of air in a path from said intake blowermeans to the front of said hood, the combination comprising: secondfilter means in the path of air from said intake blower means positionedto the front of said hood.
 6. The combination of claim 1 wherein: saidhood and working surface are inside a building, and said work surface isa heat generating cooking surface; and said blower means are outside thebuilding.
 7. The combination of claim 6 wherein: said blower meansinclude an exhaust blower removing air from under said hood, and intakeblower drawing fresh air in from outside the building.
 8. A ventilatingsystem comprising: a vent hood; exhaust means having an inlet coupled tosaid hood and including an exhaust duct and exhaust blower means forremoving air from under said hood, and of sufficient length between saidinlet and a point of discharge to atmosphere to discharge removed air tothe exterior of a building in which said hood may be disposed; intakemeans including a return duct and intake blower means introducing airadjacent said hood, said return duct being of sufficient length toenable intake of fresh air from outside a building in which said hoodmay be disposed; and by-pass means coupled between said exhaust meansand said intake means to take a portion of air from said exhaust meansupstream of said point of discharge and return it and reintroduce itadjacent the perimeter of said hood.
 9. The combination of claim 8 andfurther comprising: temperature sensor means in said return duct; adamper associated with said by-pass means; and damper operating meanscoupled to said sensor means and to said damper and responsive to highertemperatures sensed in said return duct to by-pass a smaller portion ofair from said exhaust means to said intake means.